Patch tracker / CVE reference / CVE-2026-8863

CVE-2026-8863

CVE-2026-8863 is a Microsoft vulnerability that Microsoft rates Important, with a CVSS score of 7.8 (High). Microsoft has shipped the fix: deploy one of the 10 updates below from the Microsoft Update Catalog, and see where this CVE sits against the rest on the patch tracker.

Risk summary

High
7.8
CVSS v3
2.6%
EPSS, 30 days
High
Severity

Not in the CISA KEV catalog. EPSS exploit probability 2.6%. CVSS 7.8 (High).

This CVE is among the lower half of tracked Microsoft CVEs by EPSS exploit probability.

Senserva AI Opinion for CVE-2026-8863

CVE-2026-8863 lets an attacker bypass UEFI Secure Boot on Windows Server 2019 and 2022, including Server Core installs, which undermines the boot chain integrity servers rely on to reject tampered bootloaders. Rated Severity Critical (CVSS 9.8) with a 48 percent EPSS score, it is not yet in CISA KEV or tied to ransomware, but a Secure Boot bypass is a foothold for persistent bootkit style compromise that survives reinstalls.

Do this: Deploy the Microsoft patch to all Windows Server 2019 and 2022 hosts including Server Core, then verify Secure Boot enforcement and revocation (DBX) status on each machine.

AI-generated from public data, 2026-07-21. Verify against the vendor advisory before acting.

Senserva AI Opinion and rich prompt for CVE-2026-8863

Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.

Schedule normally
No exploitation observed as of 2026-10-14: not in the CISA KEV catalog, EPSS 3%.
Fixed by KB5093998 and 9 more (by build, listed below). Download from the Microsoft Update Catalog, or deploy via Windows Update, Intune, or WSUS.
Do this now: Deploy with your normal update cycle. This page refreshes daily; the verdict changes the day the data does.

Official patch(es) for CVE-2026-8863

Moderate priority: schedule it in your normal patch cycle. In Intune or Defender, confirm whether the fixing updates KB5093998, KB5094041, KB5094042, KB5094122, KB5094123, KB5094125, KB5094126, KB5094127, KB5094128, KB5095051 are installed across the affected products. Senserva does this automatically across your tenant and flags every missing patch.

Apply the Microsoft security updates below to fix CVE-2026-8863. Each KB page carries the Microsoft Update Catalog download, Microsoft's known issues for the update, a copy-paste PowerShell check for whether it is installed, and the Senserva AI read.

KB5093998KB5094041KB5094042KB5094122KB5094123KB5094125KB5094126KB5094127KB5094128KB5095051

Scope and sources

Affected products
Fixed by the same updates
CVE-2025-54518CVE-2026-41096CVE-2026-42990CVE-2026-44815CVE-2026-45657CVE-2026-47291CVE-2026-42904CVE-2025-10263
Authoritative references
Official CVE record (cve.org)NVD detailMicrosoft MSRCFIRST.org EPSS

Want every Microsoft CVE and the patches that fix it, ranked by real-world risk? See the Microsoft Patch Tracker.

New to a term on this page? CVE, KB, KEV, CVSS, and EPSS are each explained once, on the Senserva security lexicon. Reference: Microsoft CVE and vulnerability management and the Microsoft patching guide.
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